Telugu fonts are not recognized by Blender 2.8
It seems that your font file is missing the file extension. While Windows knows that it's a TrueType font, Blender simply filters files by their file extension. Since this particular file doesn't have one, it isn't displayed in the file browser. Add the .ttf file extension to the file name and it should work properly.

Alternatively you can temporarily disable the file extension filter in Blender and the file will be visible as well.

Blender 2.80:





Blender 2.81 and later:





There may be another reason why you don't find your font file in C:\Windows\Fonts.
There are two option for installing fonts, you can either Install it (only for your user) or Install for all users. In the latter case it installs the file as expected into C:\Windows\Fonts, however in the former case it will be placed into C:\Users\[your username]\AppData\Local\Microsoft\Windows\Fonts.


Image source: Announcing Windows 10 Insider Preview Build 17704

The Windows Explorer will list all fonts when looking at C:\Windows\Fonts, including those that were installed for your user only. Therefore it's necessary to check where the file is actually stored. The easiest way to find the path is by opening the file's properties. With the file selected, right-click on it to open the context menu and select Properties. The General tab contains the Location property, which is the path to the file.